Explanation:
-A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge. It is used to cut through material, very often wood though sometimes metal or stone. The cut is made by placing the toothed edge against the material and moving it forcefully forth and less forcefully back or continuously forward.
-Square, in measurement, device consisting of two straightedges set at right angles to each other. It is used by carpenters and machinists for checking the correctness of right angles, as a guide when drawing lines on materials before cutting, or for locating holes. The tools shown in the Figure are carpenter's squares.
-Water levels have been used for many years. The water level is lower-tech than the laser level, but it can be more accurate over long distances, and works without a sightline, such as around corners.
